Totally agree with Estefanía. Carlos III has strong background in Economics and Law. There are 2 types of master provided by Spainish University: one year professional master and two years course work (could be considered as reaserch master + 3 year PhD). Most of two years masters provide stipend and tuition fees with teaching assistant or researching assistant requirement. You also don't have to worry about language because good university should have English programme. Comparing to other european countries, learning in Spain is less difficult from my point of view (Top of Spain vs German, France, Belgium, Swiss). Another suggestion for applying master scholarship is that you should broaden your interest of study to more general academic thing. Well, as you know, students often lack of working experience but small contest participation might help.

It depends. If you wanna study juridical or social sciences, it is okey. Anyway, there are so many cities in Spain with good universities where the cost of living and the price of the courses are smaller. For example: Granada, Málaga, Salamanca...